...was wondering how durable these guns are shooting large numbers of this level of .357 Magnum ammo. Or, should such be used sparingly?

Despite the rather extream views other have posted, all macines wear out. All machine wear increases proportional to the loads placed upon them (heavy loads). Nevertheless, I know of no other handgun that is likely to outlast a Blackhawk by comparison.

__________________Sometimes you get what you pay for, sometimes you only pay more for what you get.
Three shots are not a "group"...they are a "few".
If the Bible is the literal, infallible, unerring word of God...where are all those witches I am supposed to kill? (Exodus 22:18)